Presentation
Wrist pain post trauma.
Patient Data
Age: 25 years
Gender: Male
From the case:
Triquetral fracture - pooping duck sign
Lateral

A fragment of bone is present along the dorsal aspect of the proximal carpal row, adjacent to the dorsal cortex of the triquetrum.
From the case:
Triquetral fracture - pooping duck sign
Loading images...

Lateral

The scaphoid is outlined in yellow, the lunate in blue, and the visualized dorsal portion of the triquetrum in green. These structures combine to resemble a duck, with the avulsed triquetral fragment resembling poop from the duck, as indicated.
From the case:
Triquetral fracture - pooping duck sign
Frontal

Triquetral fracture is common by virtue of the fact that the dorsal stabilizing ligaments of the wrist share a common attachment site at the dorsal cortex of the triquetrum.
Case Discussion
I don't recall where I learned the pooping duck sign, but here it is in all its glory. Enjoy.